Figure 2: Antiphase boundary (APB) in a CSTO crystal.
From: Domain topology and domain switching kinetics in a hybrid improper ferroelectric
(a) The local distortions near an [110]T-oriented APB (green line) between the 1+ and 3− states, which are identical in polarization direction but differ in structure with respect to rotation (black curved arrows) and tilting (white arrows) by 180°. (b) A ab-plane DF-TEM image taken using superlattice g1+=3/2(1, 1, 0)T spot. (c) A DF-TEM image taken using superlattice g1−=3/2(−1, −1, 0)T spot. A reversed contrast in b,c demonstrates the characteristic of 180°-type FE domains. (d) A DF-TEM image taken using g1− spot at a large tilting angle to tune contrast by enhancing excitation error. A clear boundary interference fringe can then be observed between domains ii and iii, implying an inclined nature and a strong strain gradient expected in rotation-driven FEr DWs. (e) The schematic domain configuration obtained from b–d demonstrates a typical Z3 vortex pattern within a FA domain, composed of three 180°-FE domains and three DWs: FEr (red-dotted), FEt (red-solid) DWs and APB (green-solid). White arrows denote the polarization directions in FE domains. Scale bar, 500 nm.
